Re: [Qemu-block] [PATCH for-4.1] block: Use bdrv_unref_child() for all children in bdrv_close()

[Alberto Garcia]

ping

On Sun 31 Mar 2019 01:17:47 PM CEST, Alberto Garcia wrote:
> bdrv_unref_child() does the following things:
>
>   - Updates the child->bs->inherits_from pointer.
>   - Calls bdrv_detach_child() to remove the BdrvChild from bs->children.
>   - Calls bdrv_unref() to unref the child BlockDriverState.
>
> When bdrv_unref_child() was introduced in commit 33a604075c it was not
> used in bdrv_close() because the drivers that had additional children
> (like quorum or blkverify) had already called bdrv_unref() on their
> children during their own close functions.
>
> This was changed later (in 0bd6e91a7e for quorum, in 3e586be0b2 for
> blkverify) so there's no reason not to use bdrv_unref_child() in
> bdrv_close() anymore.
>
> After this there's also no need to remove bs->backing and bs->file
> separately from the rest of the children, so bdrv_close() can be
> simplified.
>
> Signed-off-by: Alberto Garcia <address@hidden>
> ---
>  block.c | 16 +++-------------
>  1 file changed, 3 insertions(+), 13 deletions(-)
>
> diff --git a/block.c b/block.c
> index 0a93ee9ac8..3b7c12d68e 100644
> --- a/block.c
> +++ b/block.c
> @@ -3842,22 +3842,12 @@ static void bdrv_close(BlockDriverState *bs)
>          bs->drv = NULL;
>      }
>  
> -    bdrv_set_backing_hd(bs, NULL, &error_abort);
> -
> -    if (bs->file != NULL) {
> -        bdrv_unref_child(bs, bs->file);
> -        bs->file = NULL;
> -    }
> -
>      QLIST_FOREACH_SAFE(child, &bs->children, next, next) {
> -        /* TODO Remove bdrv_unref() from drivers' close function and use
> -         * bdrv_unref_child() here */
> -        if (child->bs->inherits_from == bs) {
> -            child->bs->inherits_from = NULL;
> -        }
> -        bdrv_detach_child(child);
> +        bdrv_unref_child(bs, child);
>      }
>  
> +    bs->backing = NULL;
> +    bs->file = NULL;
>      g_free(bs->opaque);
>      bs->opaque = NULL;
>      atomic_set(&bs->copy_on_read, 0);
> -- 
> 2.11.0